Beyond a new look, Reddit’s first major redesign in over a decade was driven by a pressing need to update back-end systems to leverage artificial intelligence, deep learning and other digital tools, two of the website’s senior executives say.

The upgrade, unveiled earlier this month, has been a long-running conversation at the 13-year-old company, said Steve Huffman, Reddit’s chief executive officer.

“Really, since the day we launched the site, we were like ‘you know, we can do better,’” Mr. Huffman said. “The reason for the delay was nothing more than our ability to do a good job on it,” he added.

The high-trafficked website has attracted millions of users over the years who anonymously share and comment upon everything from news stories to internet memes, political opinions and conspiracy theories, via thousands of online forums.

Yet in a blog post last year, Mr. Huffman described the site as a “dystopian Craigslist.”

Clunky or not, traffic has more than doubled over the past two and half years, Mr. Huffman said, ranking it as high as the fourth most popular U.S. website. It currently has 330 million monthly active users, according to the site’s latest traffic numbers.

That steady growth has strained its back-end systems, said Nick Caldwell, the site’s vice president of engineering.

“The front-end tech is just the tip of the iceberg,” Mr. Caldwell said about the revamp. The real challenge, he said, was to “catch up on about 10 years of tech debt in about a year.”

Mr. Caldwell said the site’s modernization efforts – a process that began well over a year ago – should be familiar to chief information officers in any industry facing the challenge of overhauling a company’s legacy IT systems.

CIO Journal recently spoke with both Mr. Huffman and Mr. Caldwell about the company’s decision to drag Reddit into the age of artificial intelligence and machine learning. Edited excerpts are below:

Why did you wait so long before overhauling the site?

Mr. Huffman: The mark of a good decision is whether you regret waiting so long to do it. And I think this is a really good decision. There is always that change aversion. We believe everybody has a home on Reddit. The challenge is finding that home, particularly for new users. Helping them find their home, helping find their community and sense of belonging on Reddit, it’s something we’re not very good at. The redesign is a big effort towards making that better.

Mr. Caldwell: We also needed to staff up really, really quickly. I think you can have all the ambition in the world, but if you don’t have people to help you build it, you’re stuck. We went from 30 to around 150 engineers over the last year.

What were the key issues with the site’s back-end systems?

Mr. Caldwell: Reddit’s data pipelines were not built in a way that allowed us to understand our usage and customers. We needed to improve both the data quality and our ability to understand it.

The key thing that we did, I think a lot of CIOs and people trying to do similar deployments have, is you need one consistent view of the data. That comes down to just building a schema that the entire company agrees upon.

What makes data quality so important?

Mr. Caldwell: The current generation of tech around artificial intelligence and deep learning would have been inconceivable for us to do on our previous data stack. About a month ago, we launched our first machine-learning personalization model, and we immediately saw an eight to 10 percent increase in time on site.

Did you run into user data and privacy issues that weren’t a big concern a decade ago?

Mr. Huffman: One of the things that has been important to us, since the beginning and sometimes to the detriment of the business, is we don’t collect personal data. Mail addresses are optional. We don’t know your full name, we don’t know your address.

To the extent that we’re in the ad business, we’re finding different ways of connecting with our users, through interests and passions. So our strategy from the beginning was to minimize the surface area for that sort of risk.

Do you plan more frequent upgrades going forward?

Mr. Caldwell: I don’t think we can put up our hands and say we’re done. The situation now is that, on both the front-end and increasingly the back-end parts of our stack, we’re on extremely modern tools that allow us to develop much more quickly.

On our older back end, it took days to set up a developer environment, just to get up and running. Now it takes a matter of hours, if not minutes. We have much higher developer productivity and that means there’s going to be higher levels of throughput for new features and iterations for existing features.